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package javax.crypto.spec;

import java.security.spec.KeySpec;
import javax.crypto.SecretKey;

public class SecretKeySpec implements KeySpec,SecretKey {

  private byte[] key;
  private String algorithm;
  private int hashcode;

  public SecretKeySpec(byte[] key, int offset, int len, String algorithm){
    if (algorithm == null) {
      throw new IllegalArgumentException();
    }
    this.key = new byte[len];
    try {
      System.arraycopy(key, offset, this.key, 0, len);
    }
    catch (Exception e) {
      // E.g. key is null or offset/length is wrong
      throw new IllegalArgumentException();
    }
    this.algorithm = algorithm;
  }

  public SecretKeySpec(byte[] key, String algorithm) {
    this(key, 0, key.length, algorithm);
  }

  public boolean equals(Object obj){
    try {
      SecretKeySpec that = (SecretKeySpec)obj;
      boolean result = this.algorithm.equalsIgnoreCase(that.algorithm) && this.key.length == that.key.length;

      for (int i = 0; result && i < key.length; ++i) {
        result &= (this.key[i] == that.key[i]);
      }

      return result;
    }
    catch (ClassCastException cce) {
      return false;
    }
  }

  public String getAlgorithm(){
    return algorithm;
  }

  public byte[]getEncoded() {
    byte[] encoded = new byte[key.length];
    System.arraycopy(key, 0, encoded, 0, key.length);

    return encoded;
  }

  public String getFormat(){
    return "RAW";
  }

  public int hashCode(){
    if (hashcode == 0) {
      StringBuffer hashbuf = new StringBuffer(algorithm.toUpperCase().toLowerCase());
      for (int i = 0; i < key.length; ++i) {
        hashbuf.append((char)key[i]);
      }
      hashcode = hashbuf.toString().hashCode();
    }

    return hashcode;
  }
}